Leukotrienes are omega-6 fatty acid lipid mediators that are largely engaged in inflammatory reactions and immunological modulation. Their manufacture occurs within numerous cell types, particularly leukocytes such as neutrophils, eosinophils, mast cells, and macrophages, via the 5-lipoxygenase route. The process begins with the release of arachidonic acid from cellular membrane phospholipids, which is often enhanced by phospholipase A2 in response to various stimuli such as cell activation, damage, or immunological responses. When arachidonic acid is produced, it undergoes enzymatic conversion by 5-lipoxygenase (5-LOX) into its original metabolite, leukotriene A4 (LTA4). This phase takes place in the cytoplasm and requires the presence of the facilitator 5-LOX activating protein (FLAP). LTA4 can form leukotriene intermediates via two different pathways: LTA4 Hydrolase Pathway: LTA4 hydrolase transforms LTA4 to LTB4 (Leukotriene B4), a powerful chemoattractant for leukocytes that directs their migration to locations of inflammation or injury. LTA4 Epoxide Pathway: LTC4 synthase can conjugate LTA4 with glutathione to generate leukotriene C4 (LTC4). This phase takes place in the endoplasmic reticulum and serves as the beginning point for the synthesis of additional cysteinyl leukotrienes, such as LTD4 and LTE4. These cysteinyl leukotrienes are important for smooth muscle contraction, vascular permeability, and mucus secretion. Leukotrienes are kept intracellularly after synthesis and can be released quickly upon cellular activation. They function by attaching to particular receptors on target cells. LTB4, for example, largely binds to BLT1 and BLT2 receptors, whereas cysteinyl leukotrienes function via CysLT1 and CysLT2 receptors. The binding causes a variety of cellular responses, including chemotaxis, bronchoconstriction, enhanced vascular permeability, and immune function modification. Modulation of leukotriene production is a significant therapeutic target in asthma, allergic rhinitis, and inflammatory diseases. Pharmaceutical therapies, such as leukotriene receptor antagonists and 5-lipoxygenase inhibitors, try to reduce the impact of these potent inflammatory mediators.
